Devices for hauling, pushing or transporting wheeled objects are well known in the art. Such known devices include, for example, the following:
U.S. Pat. No. 5,082,074 describes a U-shaped, one-wheeled, motorized device for mounting to the back of a shopping cart. The U-shaped device provides motor-assisted motion of the shopping cart.
U.S. Pat. No. 4,771,840 describes an articulated shopping cart-tractor unit with a seat, especially suitable for a handicapped shopper. The tractor unit is connected to a conventional shopping cart by a bracket and coupling arrangement.
U.S. Pat. No. 5,439,069 describes a powered pusher vehicle for moving a train of nested shopping carts, the vehicle has a central drive wheel and caster wheels which balance the vehicle and provide steering and manipulation capability.
U.S. Pat. No. 4,096,920 describes a self-propelled shopping cart having a trailer for transporting a passenger standing behind the cart. The self-propelled cart can also be used as a conventional shopping cart by tilting the trailer to an upright position.
In all the prior art devices describes above, the cart is transported such that all of its wheels, e.g. 4 wheels, are in contact with the ground, in analogy to manual transportation of the cart. It should be noted that although the wheels of the cart support the weight of the cart, these wheels generally impair the steering and manipulation capability of the device during transportation of the cart.
Wheelchairs are commonly used for transporting patients in health-care related facilities such as hospitals, clinics and medical centers. It is appreciated that the personnel of the health-care facility transport patients manually over long distances and, occasionally, the patients are transported up or down slopes. This imposes an undue burden on the personal of health-care facilities.